https://scholar.dgist.ac.kr/handle/20.500.11750/10032 Thu, 05 Nov 2026 06:41:24 GMT 2026-11-05T06:41:24Z https://scholar.dgist.ac.kr/handle/20.500.11750/61073 Title: Structural heterogeneity of iron-sulfur cluster scaffold protein IscU: Metamorphic or partially folded? Author(s): Na, Jongbum; Jeong, Minchan; Kim, Jin Hae Abstract: The scaffold protein IscU plays a central role in iron-sulfur (Fe-S) cluster assembly and transfer. Despite extensive structural and biochemical research, the conformational nature of IscU remains unclear. IscU has been proposed as a metamorphic protein that interconverts between structured (S) and disordered (D) states. However, its conformational heterogeneity has often been interpreted as a consequence of intrinsic marginal stability, with the D-state described as an unfolded and functionally irrelevant state. These contrasting views highlight the fundamental challenge in defining the structural identity of IscU. In this review, we provide a comprehensive overview of the structural heterogeneity of IscU and examine how intrinsic and extrinsic factors shape the conformational equilibrium between the S- and D-states. Furthermore, we consider how these conflicting interpretations could be reconciled within an ensemble-based framework. In addition, we highlight promising approaches for characterizing the structurally elusive D-state, including high-pressure nuclear magnetic resonance, single-molecule F & ouml;rster resonance energy transfer, native ion mobility mass spectrometry, and artificial intelligence-based structural analysis, all of which provide new opportunities for probing low-populated and transient conformational states. Collectively, these perspectives suggest that the functional behavior of IscU is closely linked to its conformational heterogeneity and that a conformational landscape view may provide a more integrated understanding of its role in Fe-S cluster biosynthesis. Tue, 30 Jun 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/61073 2026-06-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60291 Title: Accurate conformational ensembles of intrinsically disordered proteins using reweighting based on NMR chemical shifts Author(s): Jeon, Juhyeong; Yang, Wonjin; Park, Sangmin; Kim, Jin Hae; Lee, Young-Ho; Yu, Wookyung Abstract: Intrinsically disordered proteins and protein regions (IDRs) underpin a wide range of vital biological processes but exhibit dynamic and heterogeneous conformations. Currently, many computational efforts seek to elucidate the conformational ensembles of these disordered proteins, yet most methods still struggle to fully capture their structural diversity. Here, we integrate structural libraries of various IDRs—derived from coarse-grained molecular dynamics (MD) simulations and machine learning models—with experimental chemical shifts obtained from NMR spectroscopy. Through a maximum entropy reweighting approach, we obtain reliable ensembles that more accurately reflect observed chemical shifts and reveal transient states. Our results highlight the importance of comprehensive sampling strategies for capturing diverse conformational states. Furthermore, we show that these weighted ensembles faithfully track conformational rearrangements under various conditions such as temperature, mutational effects, and environment, which are not fully captured by experiments alone. This approach provides a dataset encompassing each IDR’s specific structures along with their weights, offering a foundation for systematically exploring IDR structural landscapes, refining our understanding of their functional roles, and shedding light on processes related to misfolding and aggregation. Copyright © 2026 the Author(s). Sat, 31 Jan 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60291 2026-01-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59922 Title: Structural and dynamic basis of Ssp4-mediated DNA protection in foodborne bacterial spores Author(s): Seo, Minseok; Kim, Bokyung; Shin, Hyogyung; Kim, Jinwoo; Lee, Jong-bong; Ko, Young-ho; Kim, Jin Hae; Kim, Yoori Abstract: Clostridium perfringens forms metabolically dormant endospores that withstand extreme environmental conditions. Small acid-soluble proteins (SASPs) are ubiquitous DNA-binding proteins in endospores that promote resistance. While their protective role has been previously characterized, we aimed to provide further biophysical insight into the nature of these interactions, focusing on variant-specific structural dynamics through novel single-molecule and NMR approaches. Here, we characterize the DNA-binding properties and structural features of two Ssp4 variants using single-molecule fluorescence imaging and NMR spectroscopy along with electrophoretic mobility shift assays (EMSA). Both Ssp4 variants bind DNA cooperatively, but single-molecule analysis revealed preferential binding to GC-rich regions and significantly increased residence time in the presence of dipicolinic acid (DPA). NMR analysis reveals that an aspartic acid residue at position 36 (D36) stabilizes the Ssp4 structure, and its removal induces local structural perturbations without altering DNA affinity. Our findings provide molecular insights into how Ssp4 variants protect DNA in substantially dehydrated endospores and promote spore survival. © 2025 Elsevier B.V., All rights reserved. Tue, 30 Sep 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59922 2025-09-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59914 Title: Recent advances in biomolecular 19F-NMR: applications to structural characterization of Hsp90 Author(s): Kim, Jin Hae Abstract: Hsp90 is a dynamic chaperone protein whose ATP-driven conformational cycle plays critical roles in the maturation and regulation of client proteins. Due to its large size and multi-domain architecture, however, conventional structural methods provide only limited insight into its dynamic features and related functionalities. Recent advances in 19F NMR spectroscopy have enabled residue-specific and background-free monitoring of Hsp90 dynamics across multiple structural scales. This mini-review highlights three representative studies that employed 19F NMR to dissect Hsp90’s mechanistic cycle. These studies demonstrate the unique power of 19F NMR to probe conformational populations, exchange kinetics, and allosteric regulation in large protein systems. Sun, 30 Nov 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59914 2025-11-30T15:00:00Z